Imaging lens
A compact imaging lens with high-resolution, low profile, low F-value, and wide field of view, properly corrects various aberrations and comprises a first lens having positive refractive power and a convex surface facing the object side, a second lens having a meniscus shape with negative refractive power and a concave surface facing the image side, a third lens having positive refractive power and a convex surface facing the object side, a fourth lens having a meniscus shape with positive refractive power and a convex surface facing the image side, and a fifth lens having negative refractive power and a concave surface facing the image side as a double-sided aspheric lens. A pole point at an off-axial point is provided on the image-side surface, and 40<|r6/f|<90 where f: the focal length of the overall optical system and r6: curvature radius of the image-side surface of the third lens.
1. An imaging lens forming an image of an object on a solid-state image sensor, comprising in order from an object side to an image side,
a first lens having a convex surface facing the object side and a concave surface facing the image side,
a second lens having a meniscus shape and a concave surface facing the image side,
a third lens having positive refractive power and a convex surface facing the object side near an optical axis,
a fourth lens having a meniscus shape and a convex surface facing the image side, and
a fifth lens having negative refractive power and a concave surface facing the image side and the image side near the optical axis,
wherein below conditional expressions (3b), (4), (5b), and (9a) are satisfied:
0.39≤ f 1/| f 2|≤0.51 (3b)
−27< f 45/ f<− 3 (4)
0.78≤ D 4/ D 5≤1.32 (5b)
6.8< r 6/ r 7<60 (9a)
where
f: the focal length of the overall optical system of the imaging lens,
f1: focal length of the first lens,
f2: focal length of the second lens,
f45: the composite focal length of the fourth lens and the fifth lens,
D4: thickness on the optical axis of the fourth lens,
D5: thickness on the optical axis of the fifth lens,
r6: curvature radius of the image-side surface of the third lens, and
r7: curvature radius of the object-side surface of the fourth lens.
2. The imaging lens according to claim 1 ,
wherein a conditional expression (2) below is satisfied:
0.5<( T 1/ f )*100<3.1 (2)
where
f: the focal length of the overall optical system of the imaging lens, and
T1: distance along the optical axis from the image-side surface of the first lens to the object-side surface of the second lens.
3. The imaging lens according to claim 1 ,
wherein a conditional expression (6) below is satisfied:
−6.9< r 9/ r 10<−1.2 (6)
where
r9: curvature radius of the object-side surface of the fifth lens, and
r10: curvature radius of the image-side surface of the fifth lens.
4. The imaging lens according to claim 1 ,
wherein a conditional expression (7) below is satisfied:
TLA/ 2 ih< 0.9 (7)
where
TLA: total track length in air, and
ih: maximum image height.
5. The imaging lens according to claim 1 ,
wherein a conditional expression (8) below is satisfied:
0.7< ih/f< 1.0 (8)
where
f: the focal length of the overall optical system of the imaging lens, and
ih: maximum image height.
6. The imaging lens according to claim 1 ,
wherein said third lens has a convex surface facing an image side.